全文获取类型
收费全文 | 3570篇 |
免费 | 262篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 90篇 |
综合类 | 4篇 |
化学工业 | 1136篇 |
金属工艺 | 69篇 |
机械仪表 | 102篇 |
建筑科学 | 120篇 |
矿业工程 | 9篇 |
能源动力 | 134篇 |
轻工业 | 570篇 |
水利工程 | 15篇 |
石油天然气 | 13篇 |
无线电 | 218篇 |
一般工业技术 | 815篇 |
冶金工业 | 49篇 |
原子能技术 | 9篇 |
自动化技术 | 481篇 |
出版年
2023年 | 39篇 |
2022年 | 148篇 |
2021年 | 187篇 |
2020年 | 91篇 |
2019年 | 93篇 |
2018年 | 139篇 |
2017年 | 134篇 |
2016年 | 172篇 |
2015年 | 122篇 |
2014年 | 168篇 |
2013年 | 365篇 |
2012年 | 238篇 |
2011年 | 256篇 |
2010年 | 205篇 |
2009年 | 144篇 |
2008年 | 153篇 |
2007年 | 137篇 |
2006年 | 108篇 |
2005年 | 60篇 |
2004年 | 39篇 |
2003年 | 55篇 |
2002年 | 45篇 |
2001年 | 33篇 |
2000年 | 37篇 |
1999年 | 32篇 |
1998年 | 22篇 |
1997年 | 15篇 |
1996年 | 26篇 |
1995年 | 21篇 |
1994年 | 31篇 |
1993年 | 23篇 |
1992年 | 23篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 17篇 |
1988年 | 14篇 |
1985年 | 33篇 |
1984年 | 35篇 |
1983年 | 28篇 |
1982年 | 25篇 |
1981年 | 37篇 |
1980年 | 32篇 |
1979年 | 25篇 |
1978年 | 24篇 |
1977年 | 18篇 |
1976年 | 20篇 |
1975年 | 13篇 |
1974年 | 11篇 |
1973年 | 14篇 |
1972年 | 14篇 |
排序方式: 共有3834条查询结果,搜索用时 15 毫秒
121.
122.
Branko Mitrović 《Nexus Network Journal》2013,15(1):51-62
Nelson Goodman’s highly influential book Languages of Art argued that that all visual experience is merely a cultural construct. In presenting his thesis Goodman relied on a series of geometrical arguments intended to show that the geometrical construction of perspective does not rely on the geometry of light rays. In this article I analyze the geometrical validity of Goodman’s arguments. 相似文献
123.
124.
Valerije Vrček Ivana Vinković Vrček 《International Journal of Food Science & Technology》2012,47(8):1777-1783
This study was undertaken (i) to optimise and validate a suitable method for multi‐element determination in cereal products and (ii) to evaluate multi‐element content differences in commercially available conventional vs. organic wheat flours. Presented ICP‐MS method is simple and accurate for the determination of eighteen elements in cereal food. Obtained results show differences in metal content between conventional and organic wheat flours and confirm that both types of production are well within the toxicological safety limits regarding the metal contents. The significant differences among conventional vs. organic wheat flours were obtained for As, Cd, Cr, Fe, Mg, Mo, Ni and V. Toxic metals (Al, As, Cd and Pb) input was higher in conventional compared with organic wheat flours. However, further and long‐term research is needed to clearly underline the effects of organic agricultural practice on the quality of food products. 相似文献
125.
Quantum Key Recycling (QKR) is a quantum cryptographic primitive that allows one to reuse keys in an unconditionally secure way. By removing the need to repeatedly generate new keys, it improves communication efficiency. ?kori? and de Vries recently proposed a QKR scheme based on 8-state encoding (four bases). It does not require quantum computers for encryption/decryption but only single-qubit operations. We provide a missing ingredient in the security analysis of this scheme in the case of noisy channels: accurate upper bounds on the required amount of privacy amplification. We determine optimal attacks against the message and against the key, for 8-state encoding as well as 4-state and 6-state conjugate coding. We provide results in terms of min-entropy loss as well as accessible (Shannon) information. We show that the Shannon entropy analysis for 8-state encoding reduces to the analysis of quantum key distribution, whereas 4-state and 6-state suffer from additional leaks that make them less effective. From the optimal attacks we compute the required amount of privacy amplification and hence the achievable communication rate (useful information per qubit) of qubit-based QKR. Overall, 8-state encoding yields the highest communication rates. 相似文献
126.
Dragan Simić Vasa Svirčević Vladimir Ilin Svetislav D. Simić Svetlana Simić 《控制论与系统》2019,50(1):58-77
AbstractInventory management deals with a tradeoff between the benefits of keeping stocks of goods that allows fulfillment of the customer’s demand, and the cost of carrying inventory. Inventory control techniques are very important components and the most organizations can substantially reduce their costs associated with the flow of materials. This paper presents new inventory management model based on particle swarm optimization and pure adaptive search global optimization algorithm in production-inventory system. The proposed model is focusing on planned level of demand for finished goods, production and raw materials cost, production capacity as the norm, change of the production cost and inventory capital cost, all of which are typical factors in automobile manufacture industry. The model determines different factors such as the minimizing inventory quantity, minimizing inventory value, and minimizing production cost based on demand for production items. The model is tested with original real-world dataset obtained from the automotive company Lear from US and its factory in Novi Sad, Serbia. 相似文献
127.
Organic whey as a source of Lactobacillus strains with selected technological and antimicrobial properties 下载免费PDF全文
Anna Rzepkowska Dorota Zielińska Aleksandra Ołdak Danuta Kołożyn‐Krajewska 《International Journal of Food Science & Technology》2017,52(9):1983-1994
Twenty‐five strains, isolated from raw, non‐pasteurised, organic whey samples, were identified phenotypically and genotypically. Biochemical tests were performed, and enzyme profiles, antibiotic resistance and antimicrobial properties were investigated. Sixteen strains were identified as genus Lactobacillus. Based on 16S rDNA gene sequence, the strains were identified as Lb. plantarum and Lb. fermentum. All of the strains had β‐galactosidase activity, and some of them reduced nitrate content. All strains utilised carbohydrates. The tested strains were characterised by low or average lipolytic and esterolytic activity. Moreover, the strains showed low proteolytic activity which is advantageous for their use as starter cultures for foods with low protein content. Strains Lb. fermentum S20, SM1, SM3, S2R and Lb. plantarum SM5 produced harmful N‐acetyl‐β‐glucosaminidase; moreover, the strain S20 produced also β‐glucuronidase. None of the strains produced α‐chymotrypsin. In phenotypic studies, most of the test strains were susceptible to gentamicin, ampicillin, tetracycline, chloramphenicol, penicillin and erythromycin. Strains Lb. plantarum S1 and Lb. fermentum S4, S7, S8, S10, SM1 and SM3 did not possess any transfer resistance genes. Antagonistic activity of the culture LAB strains was assessed as high or moderate in relation to the indicator strains, with the greatest zones of inhibition for E.coli and the smallest for L. monocytogenes ATCC 15313. This study reveals that the LAB strains isolated from organic whey have high potential for food application. Some strains of species Lb. fermentum (S4, S7, S8, S10) have been identified as the best candidates. 相似文献
128.
Juš Kocijan Gregor Žunič Stanko Strmčnik Damir Vrančić 《International journal of control》2013,86(14):1082-1091
In the paper an approach to the non-linear control of a gas-liquid separation plant is presented. To solve the problem the fuzzy gain-scheduling method was used and implemented on a programmable logic controller (PLC). Velocity-based linearization approach was used for control system design and implementation for the first time in process control application. Emphasis was placed on the appropriate adaptation of the method and some important implementation issues. The algorithm was carefully designed and tested by using ordinary simulation, hardware-in-the-loop simulation, and experiments on the real plant. The results show that the proposed approach substantially improves the closed-loop performance of the plant. 相似文献
129.
Nevena Radojević 《Nexus Network Journal》2016,18(3):669-695
In order to create a perspective drawing on a curved surface, the quadraturista had to face, in addition to the flat perspective drawing issues, also the ones related to the mapping of the three dimensional surface. In literature we can find two methodologically different approaches related to the flat design transposition procedures onto the curved surface: indirect and direct method. The indirect one, partially described by Vignola, is based on the use of pre-designed cartoons on the ground. The direct one, described by Andrea Pozzo, is based on the direct projection of a flat grid onto the curved surface. Both the ceiling painting of the Church of San Matteo in Pisa and the parietal one of the Church of S. Caterina in Livorno show, even if observed from the privileged viewpoints, some irregularities. These irregularities, as we are going to show, are actually the consequences of the method applied for the transposition of the flat drawings onto the curved surfaces. 相似文献
130.
Adam Pietras Aleksandra Węglowska Beata Rams Marek Węglowski 《Welding International》2016,30(2):112-118
The article presents the results of research on the use of the new technology of friction welding with a non-wearing tool for welding pipe ends with lids. The pipes and lids were made of aluminium alloy EN AW 2017A, non-weldable by conventional methods. The aim of the study was to verify the possibility of welding the lid to the pipe using the FSW method as well as a new method with a tool with specially profiled friction surface. The article presents the results of structural tests and strength tests of the weld joints obtained using the new technique. 相似文献